1. Field of the Invention
The present invention relates to a broadcast receiving apparatus. More specifically, a broadcast receiving apparatus that receives broadcast signals including print information and a method of controlling the apparatus.
2. Description of the Related Art
Print service for data broadcasts is provided as one type of data broadcast service in digital terrestrial broadcasting. Users of digital televisions (DTVs) having a function of controlling printing apparatuses (for example, printers) connected to the DTVs can use the print service to print print content items, such as information concerning broadcast programs, weather forecast, or news, using the printers. Digital broadcasting standards and operational guidelines concerning the print service are described in, for example, Association of Radio Industries and Businesses Standard “Data Coding and Transmission Specification for Digital Broadcasting” ARIB STD-B24 4.4 and Association of Radio Industries and Businesses Technical Report “Operational Guidelines for Digital Terrestrial Television Broadcasting” ARIB TR-B14 2.7. The ARIB STD-B24 4.4 and ARIB TR-B14 2.7 can be acquired from the Web site of Digital Broadcasting Experts Group. The version numbers that can be acquired from the above site are 5.1 for the ARIB STD-B24 and 2.8 for the ARIB TR-B14 because of revisions of the ARIB standard and technical report. In other words, although the version numbers described in the basic Japanese application are different from those acquired from the above site when the present application is filed, no major difference is found in the description concerning the print service between the ARIB STD-B24 4.4 and the ARIB STD-B24 5.1 and between the ARIB TR-B14 2.7 and ARIB TR-B14 2.8. The following three print modes are applicable to DTVs in the print service conforming to the above documents.    Print mode (1): The DTVs acquire print data included in broadcast waves and request printers to print the print data.    Print mode (2): The DTVs capture data broadcast images that are being displayed and request printers to print the data broadcast images.    Print mode (3): The DTVs request printers to print print data provided in servers on the Internet.
The print mode (1) is realized by printFile( ) or printTemplate( ), which are extension functions DOM-API defined in the above standard and operational guidelines. The printFile( ) is used by a DTV to acquire print data (printfile print data) from a transport stream (TS) resulting from reception and demodulation of a broadcast wave, to transfer the print data to a printer, and to request the printer to print the print data. The DOM-API is an abbreviation of Document Object Model-Application Program Interface.
The print mode (2) is realized by printStaticScreen( ), which is an extension function DOM-API defined in the above standard and operational guidelines.
The print mode (3) is realized by printUri( ), which is an extension function DOM-API defined in the above standard and operational guidelines. The printUri( ) is used by a DTV to cause a printer to acquire print data (printUri print data) indicated by the Uniform Resource Identifier (URI) specified by an argument of the printUri( ) and to request the printer to print the print data.
Apparatuses of determining whether print content items indicated by URIs are tampered when the print content items are printed are known in recent years (for example, refer to Japanese Patent Laid-Open No. 2006-126912). If the print content items are tampered, such apparatuses notify creators of the print content items or print requesters that the print content items are tampered by telephones or electronic mails.
The apparatus disclosed in Japanese Patent Laid-Open No. 2006-126912 adopts the following three methods of determining whether a print content item is tampered.    Determination method (1): Determination using checksum    Determination method (2): Determination based on the final update time of the print content item or generation management information by, for example, a Concurrent Version System (CVS)    Determination method (3): Determination using a watermark message in the print content item
The printUri( ) print data generally exists in a content server on the Internet. Accordingly, a recording apparatus, such as a hard disk recorder (HDR), recording the TS records the printfile print data but does not record the printUri print data.
The printUri print data indicated by URIs recorded in the HDR can be deleted from the content server or can be replaced with another printUri print data after the broadcast program ends. Accordingly, the following two error events can occur if a request to print printUri print data is executed while a user is viewing a program recorded in the HDR.    Error event (1): The printing cannot be performed because the printUri print data indicated by a recorded URI is deleted    Error event (2): The printUri print data indicated by a recorded URI is replaced with another data and a print content item that is not desired by a broadcasting station or a user is printed
If the error event (1) or (2) occurs, problems occur in which the user wastes ink or sheets of paper and it takes excessive time for the printing.
In order to resolve the above problems, the deletion or replacement of the printUri print data by using the technology disclosed in Japanese Patent Laid-Open No. 2006-126912 may be detected. However, the use of the technology disclosed in Japanese Patent Laid-Open No. 2006-126912 can cause problems in which the system is made complicated and the cost is increased in association with the complicated system due to the following three reasons.    Reason (1): when the determination method (1) is used, it is necessary for the recording apparatus to have a function of calculating the checksum of the print content item when a program (that is, a TS) is recorded and holding the checksum in association with the TS.    Reason (2): when the determination method (2) is used, it is necessary to separately provide, for example, the CVS.    Reason (3): when the determination method (3) is used, it is necessary for the recording apparatus to have a function of acquiring a watermark message in the print content item when a program (that is, a TS) is recorded and holding the watermark message in association with the TS.